Effort modulation for process control of friction stir operations

Abstract

A system and method for making adjustments to output effort from a spindle driver using a multi-stage nested control loop of an active controller to provide constant power to a friction stir zone during a friction stir operation. Providing constant power facilitates temperature control within the friction stir zone and thereby improves the result of the operation

What is claimed is: 
     
         1 . A method for using an active controller to control a friction stir zone, said method comprising:
 providing an active controller for controlling operation of a friction stir tool; and   controlling, to a power setpoint, power provided by the friction stir tool to a friction stir zone using the active controller, the power provided to the friction stir zone is controlled by making adjustments to an output effort of a spindle driver that is used to drive the friction stir tool.   
     
     
         2 . The method as defined in  claim 1 , wherein controlling the power provided to the friction stir zone further comprises using the active controller to maintain a power input level. 
     
     
         3 . The method as defined in  claim 1 , further comprising implementing a multi-stage nested control loop. 
     
     
         4 . The method as defined in  claim 3 , wherein the implementing the multi-stage nested control loop further comprises:
 1) implementing an inner control loop to thereby maintain a power input level through control of the output effort of the spindle driver; and   2) implementing an outer control loop that adjusts the power provided to thereby maintain a temperature for the friction stir zone.   
     
     
         5 . The method as defined in  claim 1 , wherein controlling the output effort of the spindle driver further comprises controlling an input flow to the spindle driver. 
     
     
         6 . The method as defined in  claim 1 , wherein controlling the output effort of the spindle driver further comprises maintaining an effort level. 
     
     
         7 . The method as defined in  claim 1 , wherein controlling the output effort of the spindle driver further comprises stabilizing control of the spindle driver. 
     
     
         8 . The method as defined in  claim 7 , wherein stabilizing control of the spindle driver further comprises using spindle flow feedback. 
     
     
         9 . The method as defined in  claim 1 , wherein maintaining the power input level through control of the output effort of the spindle driver further comprises increasing the output effort of the spindle driver in response to a decrease in the spindle flow. 
     
     
         10 . The method as defined in  claim 1 , wherein maintaining the power input level through control of the output effort of the spindle driver further comprises decreasing the output effort of the spindle driver in response to an increase in the spindle flow. 
     
     
         11 . The method of  claim 1 , wherein the friction stir tool is a welding tool. 
     
     
         12 . A friction stir system, comprising:
 a friction stir tool;   a spindle coupled to the friction stir tool;   a spindle driver coupled to the spindle to thereby cause the friction stir tool to rotate; and   an active controller for controlling, to a power setpoint, operation of the friction stir tool, the active controller configured to adjust an output effort of the spindle driver that is used to drive the friction stir tool to thereby control power provided to a friction stir zone.   
     
     
         13 . The system of  claim 12 , wherein the active controller is further comprises means for receiving spindle flow feedback. 
     
     
         14 . The system of  claim 12 , wherein the active controller is further configured to approach and maintain a temperature for the friction stir zone. 
     
     
         15 . The system of  claim 12 , wherein the active controller comprises a multi-stage nested control loop. 
     
     
         16 . The system of  claim 15 , wherein the multi-stage nested control loop comprises an inner control loop configured to maintain a power input level through control of the spindle driver effort, and an outer control loop that adjusts the power provided to thereby maintain a temperature in the friction stir zone. 
     
     
         17 . The system of  claim 12 , wherein the friction stir tool is a welding tool. 
     
     
         18 . A method, comprising:
 controlling, to a power setpoint, power provided by a friction stir tool to a friction stir zone using an active controller, the power provided to the friction stir zone is controlled by making adjustments to an output effort of a spindle driver that is used to drive the friction stir tool.   
     
     
         19 . The method of  claim 18 , wherein controlling the power provided to the friction stir zone includes using the active controller to maintain a power input level. 
     
     
         20 . The method of  claim 18 , further comprising:
 using a multi-stage nested control loop.